Nowadays, a dumbbell with a handle strap is available in the market, in which the handle strap is connected to opposite ends of the handle of the dumbbell. A user, who is going to do walking/running exercise, can hold the dumbbell handle with his hand which is constrained by the strap, and can do an exercise with a dumbbell in his hand as his hand sways forwardly and backwardly. At this time, the handle strap can prevent the dumbbell from slipping off and provide a sense of safety. The handle strap can be fixedly or detachably connected to the dumbbell handle. In a detachable connection, the dumbbell becomes a conventional one so long as the handle strap is detached therefrom.
However, in the case of the existing dumbbells with a detachable handle strap, it is necessary to take down the whole head portions in order to connect or disconnect the handle strap to/from the dumbbell handle, which takes more time and is inconvenient in use. Moreover, the dumbbell is lack of additional functions. It is a need, therefore, to provide a dumbbell with an improved design and some more functions.